The present invention relates to automotive fuel tanks and, in particular, to a plastic fuel tank having woven fabric reinforcements encapsulated on the exterior surface thereof.
Conventional automotive fuel tanks can be classified into two distinctive design approaches. The first, and most widely utilized design approach includes the fabrication of two or more metallic (i.e. steel) stampings which are roller (i.e. continuous) seam welded together to form a leak-proof tank. Likewise, metal fuel tanks are typically plated with a corrosion resistant metal (i.e. terne plate) which acts as a barrier against attack from corrosive gasoline ingredients. With recent government mandates directed to the elimination of lead as an octane boost additive in gasoline, it will be necessary for the industry to mix other additives such as methyl-alcohol or methanol with gasoline. Both are by-products of the gasoline distillation process and could be easily added to the gasoline end-product. However, such additives are extremely corrosive to conventional stamped metal fuel tanks.
Another known disadvantage of welded steel tanks is the need to produce leak-proof seams which are capable of withstanding impact as well as extremely high internal pressure levels without rupturing. Additionally, metal tanks do not, in and of themselves, provide adequate thermal insulation from excessive heat generated by adjacent exhaust system components. In some instances, an additional non-metallic shield member is provided between the tank and the exhaust system components to thermally insulate the steel tank, thereby reducing the transfer of heat from the exhaust components to the fuel confined within the tank.
The application of plastics in the fabrication of fuel tanks is the second design approach which has recently gained recognition in the automotive industry. In recent years, the selection of plastic as a material from which fuel tanks, particularly motor vehicle fuel tanks, can be fabricated has received increased interest. Plastic fuel tanks are typically less expensive than metal tanks, are easier to produce, and are more resistant to the deteriorating effects of gasoline and the environment. In addition, because plastic fuel tanks can be more readily formed into complex shapes, it is possible to specially configure plastic fuel tanks and thereby significantly increase the capacity of the tank for a given application. Moreover, plastic fuel tanks are more impact resistant than metal tanks and less prone to rupturing as the blow molding process does not produce seams which must be subsequently joined and sealed.
However, to ensure adequate strength of the fuel tanks, particularly with plastic fuel tanks having complex shapes, it is frequently necessary to fabricate the entire fuel tank with a greater average wall thickness than necessary to ensure appropriate wall thickness in those localized areas where the blow molding manufacturing process tends to cause thinning.
It is therefore an object of the present invention to provide an improved one-piece blow molded plastic fuel tank having fabric reinforcements encapsulated at localized points on the exterior surface of the tank. The fabric reinforcements provide additional mechanical strength, particularly at elevated temperatures. Furthermore, the fabric reinforcements are able to strengthen localized areas which have been "deep drawn" and where wall sections tend to be thinnest. Likewise, it is preferred to utilize material for such reinforcements that additionally provides a heat shield effect for thermally insulating the contents of the fuel tank from exhaust systems components.
It is an additional object of the present invention to provide a reinforced blow molded fuel tank that can be manufactured with a reduced average overall wall thickness thereby reducing the weight of the fuel tank without sacrificing the strength and integrity of the fuel tank.
Other advantages and features will become apparent from the following specification taken in connection with the accompanying drawings.